The Link Between Hydrogen Sulfide and Gut Issues (IBD/IBS) - Part 2: Causes

2 minute read

In part 1 we discussed how an impaired sulfur metabolism can lead to an overgrowth of sulfur-reducing bacteria (SRB). These bacteria produce hydrogen sulfide as a byproduct which can contribute to health issues including IBS and IBD. In part 2 we will go over the potential causes that can screw up sulfur metabolism and contribute to this bacterial overgrowth.

The process of converting dietary sulfur into sulfate is quite a complex one. If anything interferes with it then there’s going to be issues getting the necessary sulfate that we need.

Vitamin and Mineral Deficiencies

A key component of the conversion of sulfur to sulfate is the Sulfite Oxidase (SUOX) enzyme. It depends on the minerals iron and molybdenum to be produced. Being deficient in these minerals can therefore lead to a decreased production of the SUOX enzyme and a decreased ability to convert sulfur into sulfate.

B12 is an important vitamin for the methylation cycle which is linked to the sulfation pathway. Being deficient in vitamin B12 will slow down the methylation cycle and therefore affect sulfation.


A healthy, diverse microbiome is a good defence against opportunistic bacteria overgrowing and causing issues. Even though SRB may be trying to assist the body, the argument can still be made that their numbers can get more out of control when not kept “in check” by beneficial bacteria. This dysbiosis can be brought about in many different ways, some of which include antibiotic use, lack of fermented foods or prebiotic fibres in the diet, or having a C-section at birth.

Toxic Exposures

Sulfate is incredibly important for detoxification, so toxic exposures in our environment, food and water can increase the demand for sulfate. We live in a world where detoxification is more important than ever. Our bodies have the ability to handle toxic exposures, however we need sulfate in order to do so. This increased demand for sulfate must be met with an increase in supply, putting more pressure on our sulfur metabolism. Some examples of toxic exposures include heavy metals, mold and chemicals like chlorine and fluoride.


A particular chemical that impacts all of the above factors is glyphosate, the active ingredient in the pervasive herbicide RoundUp. Glyphosate binds to a large number of key minerals including iron1 and potentially molybdenum which are both required for the SUOX enzyme, in addition to cobalt which is a cofactor for B12. Glyphosate is considered an antibiotic because it preferentially kills off beneficial bacteria and leaves the pathogens alone, contributing heavily to dysbiosis2.

Lack of Sunlight

I also believe a lack of sunlight exposure and the use of sunscreens could be contributing to this problem. MIT researcher Stephannie Seneff wrote a great paper where she makes a case for cholesterol sulfate being the main benefit of sunlight exposure and that sunlight is able to oxidize hydrogen sulfide into sulfate3. Additionally, the aluminium in sunscreens is known to suppress CYP enzymes which are likely crucial for sulfate synthesis.


There are likely many other factors that can lead to impaired sulfur metabolism such as genetics and imbalances in the nervous system, but these are the ones I have found to have such a direct impact. Now that we have an idea of what could be causing this issue, in part 3 I will be going over my experience trying to fix sulfur metabolism and reduce the overgrowth of SRB.